Resistive and hybrid control schemes for haptic feedback interface devices

ABSTRACT

A method is disclosed that includes outputting haptic feedback based on a movement of an object in a first direction from a first position to a second position. The haptic feedback is discontinued when the object is moved in a second direction opposite the first direction subsequent to the movement in the first direction. The haptic feedback is output again when the object moves past the second position in the first direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Patent Application No.60/533,129, entitled “Hybrid and Resistive Haptic Effects,” filed onDec. 30, 2003, the entirety of which is incorporated herein byreference.

BACKGROUND

The invention relates generally to control schemes for haptic feedbackinterface devices, and more particularly to resistive and hybridactuator control schemes for haptic feedback interface devices.

Haptic feedback interface devices are used for a variety of differentfunctions and are often used with a variety of computer systems. Forexample, haptic feedback interface devices are used with computercontrolled simulations, games, and other application programs. Acomputer system typically displays a graphical environment to a user ona display screen or other output device. The user can interact with thedisplayed environment to play a game, experience a simulation or“virtual reality” environment, or otherwise influence events or imagesdepicted on the screen or in an application program or operating system.Such user interaction can be implemented through an interface device,such as a joystick, “joypad” button controller, mouse, trackball, stylusand tablet, foot or hand pedals, control knob, touch panel, etc., thatis connected to the computer system. The computer updates the graphicaldisplay in response to manipulation of the interface device and provideshaptic feedback based on manipulation and/or movement of the object.Examples of such interface devices are disclosed in U.S. applicationSer. No. 10/285,450, entitled “Method and Apparatus for ProvidingTactile Sensations,” which is incorporated herein by reference in itsentirety.

The haptic feedback provided by the interface device is often output viaactuators in the interface device. These actuators typically includeeither an active actuator or a resistive actuator, depending upon thedesired haptic effect. In addition, interface devices exist that includeboth resistive and active actuators (i.e., hybrid interface devices).Such interface devices, however, often use the different types ofactuators to output feedback that is actuator dependent. In other words,the resistive actuator is used to output one type of feedback and theactive actuator is used to output a different type of feedback.

A need exists, however, for improvements in interface devices andcontrol schemes for interface devices that use resistive and activeactuators to produce desired haptic effects.

SUMMARY OF THE INVENTION

A method is disclosed that includes outputting haptic feedback based ona movement of an object in a first direction from a first position to asecond position. The haptic feedback is discontinued when the object ismoved in a second direction opposite the first direction subsequent tothe movement in the first direction. The haptic feedback is output againwhen the object moves past the second position in the first direction.

In other embodiments, a device is disclosed that includes an objectdisplaceable in at least one degree of freedom with respect to a firstreference point. A sensor is configured to output a position signalassociated with a displacement of the object, the displacement being oneof a first displacement, a second displacement and a third displacement.An actuator is configured to output a resistive force based on theposition signal, the resistive force being associated with the firstdisplacement of the object in a first direction away from the firstreference point until the object is moved to a position. The resistiveforce is discontinued when the position signal is associated with thesecond displacement in a second direction opposite the first direction.The resistive force is further output after the third displacement inthe first direction past the position, subsequent to the object beingmoved in the second direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a haptic feedback interfacedevice according to an embodiment of the invention.

FIG. 2 is an illustration of a device according to an embodiment of theinvention.

FIG. 3 is an illustration of a force profile associated with a controlscheme according to an embodiment of the invention.

FIG. 4 is an illustration of a force profile associated with a controlscheme according to a further embodiment of the invention.

FIG. 5A is an illustration of a force profile associated with a controlscheme for a hybrid interface device according to an embodiment of theinvention.

FIG. 5B is an illustration of a force profile associated with a controlscheme for a hybrid interface device according to an embodiment of theinvention.

FIG. 6A is an illustration of a force profile associated with a controlscheme associated with direction-dependent detents for a hybridinterface device according to an embodiment of the invention.

FIG. 6B is an illustration of a force profile associated with a controlscheme associated with direction-dependent detents for a hybridinterface device according to another embodiment of the invention.

FIG. 7 is a schematic representation of a hybrid interface deviceaccording to an embodiment of the invention.

FIG. 8 is a schematic representation of a hybrid interface deviceaccording to another embodiment of the invention.

FIG. 9A is an actuator command associated with a force profile of aninterface device without demagnetization.

FIG. 9B is the actuator response of the interface device based on theactuator command shown in FIG. 9A.

FIG. 9C is an actuator command associated with demagnetization of aninterface device according to an embodiment of the invention.

FIG. 9D is the actuator response of the interface device based on theactuator command shown in FIG. 9C, including a demagnetization pulse.

DETAILED DESCRIPTION

FIG. 1 is a schematic representation of an interface device 10 accordingto an embodiment of the invention. The interface device 10 includes amanipulandum or an object 20 that is coupled to a sensor 25 and ismovable in at least one degree of freedom. The sensor 25 is configuredto output sensor signals to a microcontroller 27. The microcontroller 27outputs signals to an actuator 40 based on at least one of the position,velocity, direction, force, torque and acceleration of the object 20.

In some embodiments of the invention, the microcontroller 27 includes aprocessor 30 having a processor readable medium 35. The processor 30 isconfigured to receive signals from the sensor 25, and output signals tothe actuator 40. The processor 30 can be, for example, a commerciallyavailable personal computer, or a less complex computing or processingdevice that is dedicated to performing one or more specific tasks. Forexample, the processor 30 can be dedicated to providing an interactivevirtual reality environment.

The processor 30, according to one or more embodiments of the invention,can be a commercially available microprocessor. Alternatively, theprocessor 30 can be an application-specific integrated circuit (ASIC) ora combination of ASICs, which are designed to achieve one or morespecific functions, or enable one or more specific devices orapplications. In yet another embodiment, the processor 30 can be ananalog or digital circuit, or a combination of multiple circuits.

In some embodiments, the processor 30 includes the processor readablemedium 35. The processor readable medium 35 can include one or moretypes of memory. For example, the processor readable medium 35 caninclude a read only memory (ROM) component and a random access memory(RAM) component. The processor readable medium 35 can also include othertypes of memory that are suitable for storing data in a form retrievableby the processor 30. For example, electronically programmable read onlymemory (EPROM), erasable electronically programmable read only memory(EEPROM), flash memory, as well as other suitable forms of memory can beincluded within the processor readable medium 35. The processor 30 canalso include a variety of other components, such as for example,co-processors, graphics processors, etc., depending upon the desiredfunctionality of the interface device 10.

The processor 30 is in communication with the processor readable medium35, and can store data in the processor readable medium 35 or retrievedata previously stored in the processor readable medium 35. Thecomponents of the processor 30 can communicate with devices external tothe processor 30 by way of an input/output (I/O) component (not shown inFIG. 1). According to one or more embodiments of the invention, the I/Ocomponent can include a variety of suitable communication interfaces.For example, the I/O component can include, for example, wiredconnections, such as standard serial ports, parallel ports, universalserial bus (USB) ports, S-video ports, local area network (LAN) ports,small computer system interface (SCSI) ports, and so forth.Additionally, the I/O component can include, for example, wirelessconnections, such as infrared ports, optical ports, Bluetooth® wirelessports, wireless LAN ports, or the like.

The processor 30 is configured to receive signals from the sensor 25 andoutput signals to the actuator 40. The processor 30 receives data valuesassociated with the position, orientation, movement, velocity,acceleration, etc. of the object 20. In alternative embodiments,multiple sensors (not shown) can be used to determine the state of theobject 20. In some embodiments of the invention, the sensors can detectmultiple degrees of freedom of the object (e.g., translation, pitch,yaw, rotation, etc.). Interface device 10 can be implemented such thatthe object 20 is, for example, a joystick, trackball, mouse, gamecontroller, knob, wheel, button, etc.

Several control schemes are useful to control the output of hapticfeedback from the interface device 10 via particular actuator and objectconfigurations. In one embodiment, for example, the object 20 is a knobor wheel and a control scheme is provided to output simulated detentforce profiles. Haptic feedback effects for knobs are disclosed in U.S.patent application Ser. No. 10/641,243, entitled “Haptic FeedbackEffects for Control Knobs and Other Interface Devices,” which isincorporated herein by reference in its entirety.

In one embodiment of the invention, control schemes are used inconjunction with a resistive actuator to provide a desired hapticeffect. An actuator 40 is provided for each object 20 that includeshaptic feedback functionality. In some embodiments, additional actuatorscan be provided for each degree of freedom of object 20. Actuator 40,can be an active actuator, such as a linear current control motor,stepper motor, pneumatic/hydraulic active actuator, a torque motor(motor with limited angular range), voice coil actuator, etc. Passiveactuators can also be used, including magnetic particle brakes, frictionbrakes, or pneumatic/hydraulic passive actuators, and generate a dampingresistance or friction opposite a direction of movement of object 20.Resistive actuators, as discussed herein, include passive actuators.Active actuators, as discussed herein, include assistive actuators.

One implementation of a control scheme according to the inventionincludes controlling the haptic feedback based on the velocity of theobject 20 (e.g., a knob). In such an implementation, detents output withresistive actuators can have a drawback when moving at high speeds. Thesimple position-based detent output via resistive actuators provides asufficiently realistic and acceptable sensation at low speeds. When theobject 20 is moved quickly, however, the detents are perceived at a muchlower magnitude. One way to compensate for this effect is to make themagnitude of the detents a function of the velocity. As the velocityincreases, so does the peak torque of the detents.

Referring to FIGS. 2 and 3, a control scheme according to an embodimentof the invention includes resetting a boundary of a virtual barrierencountered during movement of an object 200. The forces output can be,for example, simulated spring forces, and can be associated with anevent in a graphical environment. For example, the movement of theobject 200 may be associated with a movement of a graphical object on adisplay, such as in a video game. The barrier may include a wall in thesame video game that is contacted by the moving graphical object. In theillustrated embodiment, the object 200 is a knob, but any object movablein at least two directions can be used (e.g., a joystick, a mouse, etc).The forces output by the actuators can also be used in otherapplications, such as a simulated radio tuning knob. When the knobreaches the end of the frequency range of the radio, force is output tosimulate reaching the end of the range. In such an embodiment, the“barrier” is the end of the frequency range of the radio. As the knobcontinues to be turned in that same direction, force will continue to beoutput. When the knob is turned in the opposite direction, back acrossthe range of radio frequencies, the resistive force is discontinued andthe barrier position is reset as discussed above. The force is againoutput when the knob is turned back towards the end of the frequencyrange at the point where the knob engages the reset barrier position.

As the object 200 is moved through various positions, the output of theactuator can be modified. The object starts at position P₀ at a time t₀.As the object 200 is moved in a first direction away from its originalposition P₀ to a second position P₁ at time t₁, no force is output bythe actuator 40. As the object contacts a barrier at the barrierposition P₁, a resistive force is output by the actuator 40 based on themovement and/or position of the object 200 until the object reachesposition P₂ at time t₂. The force that is output during the movement ofthe object 200 from position P₁ at time t₁ to position P₂ at time t₂ canbe a constant resistive force as illustrated in FIG. 3 or a resistiveforce proportional to the distance of penetration into the virtualbarrier (not illustrated).

The haptic feedback is discontinued when the object 200 is moved in thesecond direction opposite the first direction (i.e., when the object ismoved from P₂ at time t₂ to P₁ at time t₃. When the object 200 stops atposition P₁, position P₂ is reset as the position of the barrier. Thus,it is not necessary to move the object 200 back through the previouslypenetrated distance into the barrier. When the object is moved back inthe first direction, from P₁ to P₂, no force is output until the objectreaches the new position of the barrier, P₂, at time t₄. When the object200 reaches position P₂ at time t₄, the resistive force is output untilthe object reaches position P₃. When the object 200 reaches position P₃,the force output can be discontinued if the object is moved back in thesecond direction. Alternatively, the object 200 can continue to be movedin the first direction, thus continuing to output the resistive force.

In an alternative embodiment of the invention, haptic feedback can beoutput when the object 200 is moved in the second direction (e.g., fromP₂ to P₁). The haptic feedback that is output when the object 200 ismoved in the second direction can be different than the haptic feedbackassociated with movement of the object 200 in the first direction. Forexample, the haptic feedback associated with the movement of the object200 in the first direction can be a constant resistive force and thehaptic feedback associated with the movement of the object 200 in thesecond direction can be a simulated detent represented by the dashedline in FIG. 3.

In another embodiment of the invention, position reset can beaccomplished for the output of a detent. For example, when resistiveactuators are used to output detent forces, a user will often releasethe object or manipulandum when the object is positioned off the centerof the detent. Without position reset, the first detent output when theobject is next engaged is not consistent with other detent outputsbecause the object did not start in the center of the detent. To providemore consistent initial detent interaction with a resistive actuator,the position of the object is redefined to be the center of the detentafter the user has released the object. The release of the object can bedetected in various ways. For example, a sensor could be used to detectwhen contact with the object has ended. Alternatively, the centerposition can be reset after the object has not been moved for a periodof time.

Another implementation of a force profile associated with a controlscheme according to an embodiment of the invention includes using aresistive actuator to create an assistive sensation. Referring to FIG.4, the resistive actuator can be set to output a given level of force.At some point, such as a predetermined location or orientation A₁, or ata predetermined time, the resistive actuator abruptly reduces the amountof force being output to zero, for example, thereby reducing to almostzero the friction on the object. Such an abrupt reduction in the outputforce provides the sensation of an assistive force. When the object 20is moved out of the predetermined location or orientation to anotherlocation or orientation A₂, the resistive force is again output. Thelocations or orientations A₁, A₂ can be associated with simulatedinteractions in a graphical environment or can be time-based.

In another embodiment of the invention, control schemes are used inconjunction with a resistive actuator and an active actuator to providea desired haptic effect, such as a simulated detent. Interface devicesthat use both assistive and resistive actuators can be referred toherein as “hybrid” interface devices.

Examples of force profiles associated with control schemes that can beused with hybrid interface devices to output simulated detent forces areillustrated in FIGS. 5A, 5B, 6A and 6B. Referring first to FIG. 5A, anexample of a force profile associated with a control scheme isillustrated in which an assistive force is continuously output by theassistive actuator and is based on the position of the object. Atpredetermined locations, also based on the position of the object, aresistive force provided by the resistive actuator is superposed on theassistive force. The collective effect from the assistive and resistiveforces provides an enhanced detent sensation.

FIG. 5B illustrates another example of a force profile associated with acontrol scheme in which both assistive and resistive actuators are usedto output a simulated detent force. In the illustrated control scheme,both active and resistive forces are both continuously output based onthe position of the object to obtain the desired detent sensation.

FIGS. 6A and 6B illustrate examples of force profiles associated withcontrol schemes for use with a hybrid device to providedirection-dependent detents. For example, FIG. 6A illustrates an exampleof a force profile associated with a control scheme in which assistiveforces and resistive forces are output in an alternating manner based onthe position of the object. For example, as an object is moved from leftto right, an assistive force will be applied over a certain distance,followed by a resistive force applied over a distance. FIG. 6Billustrates an example of a control scheme in which assistive forces andresistive forces are output in an alternating manner based on theposition of the object. In the illustrated embodiment of FIG. 6B,however, the assistive force is applied in the opposite directionbecause the object is moved in the opposite direction. For example, asthe object is moved from right to left, an assistive force will beapplied over a distance in the direction opposite the direction theassistive force applied when the object is moved from left to right,followed by a resistive force applied over a distance.

Hybrid devices have at least one active actuator and at least oneresistive actuator coupled to the object 20 to provide different forceeffects as described above. Both of these actuators have differentfiltering requirements with respect to the signals generated by thesensor coupled to the object (e.g., position signals, velocity signals,acceleration signals). For the assistive force component of the signal,a balance between the delay and the smoothness of the signal should beachieved. Too much delay in the signal can result in instabilities ofthe device, while too much noise in the signal can result in unwantedtextures that can be perceived by the user. For delay purposes, avelocity signal can be filtered at frequencies of at least approximately100 Hz, for example.

The filtering requirements for the resistive force component aredifferent from the filtering requirements for the assistive forcecomponent. Because the resistive force component of the signals outputby the sensor is inherently stable, the filtering can be much moreaggressive, resulting in a smoother signal. The velocity signal for theresistive component can be low passed at approximately 10 Hz, forexample. Regardless of the particular type of signal and the frequenciesat which the two components are filtered, the active component istypically filtered at a higher frequency than the resistive component.

The signal filtering can be accomplished using various configurations.For example, referring to FIG. 7, one filter 700 can be used. In such aconfiguration, the single filter performs different functions dependingon whether the signal being filtered is associated with the activeactuator 400 or the resistive actuator 450. Alternatively, referring toFIG. 8, two separate filters can be used. One filter 800 is associatedwith the active actuator 400 and another filter 850 is associated withthe passive actuator 450. The different filters 800, 850 performdifferent functions based on the actuator with which they areassociated.

One concern with some embodiments of interface device described hereinis that as the interface device 10 is being used, it can becomemagnetized over time depending on the materials used to construct theinterface device 10. As the actuator is repeatedly actuated, theactuator “sticks” because it becomes magnetized. In other words, theresistive actuator doesn't release quickly enough, thereby creating the“stickiness” discussed above. This is due to residual magnetization,which produces a friction level higher than the base line friction inthe actuator. To improve the resistive actuator performance, theresidual magnetization can be eliminated.

FIGS. 9A and 9B illustrate the actuator command 910 and actuatorresponse 920 of an interface device without demagnetization,respectively. When the actuator command 910 is set to zero after detentsare output, the friction level of the actuator response 920 due to theresidual magnetization is higher than the friction before the detentswere output as illustrated in FIG. 9B.

The interface device can be demagnetized by reversing the polarizationof the magnetic field for successive simulated detents to demagnetizethe interface device (i.e., applying a demagnetization pulse 950). Thestandard method of demagnetization is to apply a decaying sinusoidpulse. In some embodiments, a single pulse is used to demagnetize theactuator. The demagnetization pulse 950 is a negative pulse of certainsize and duration that will improve the demagnetization of the actuator.FIG. 9C illustrates the actuator command 910′ including application ofthe demagnetization pulse 950, and the associated actuator response920′. Once the demagnetization pulse 950 is applied, the friction in theactuator returns to the level it was at before the detents were outputas illustrated in FIG. 9D.

In addition to the polarity of the voltages alternating at eachsubsequent position, the magnitude of the voltage output may vary witheach successive detent. If a given pulse of duration Δt and magnitude ΔMdemagnetizes the actuator, a pulse of reduced Δt and increased ΔM willwork as well. The varying magnitude may be based on the position of theobject with respect to a reference point or origin position. Themagnitude may also vary based on the range of motion through which theobject travels.

CONCLUSION

While various embodiments of the invention have been described above, itshould be understood that they have been presented by way of exampleonly, and not limitation. Thus, the breadth and scope of the inventionshould not be limited by any of the above-described embodiments, butshould be defined only in accordance with the following claims and theirequivalence.

The previous description of the embodiments is provided to enable anyperson skilled in the art to make or use the invention. While theinvention has been particularly shown and described with reference toembodiments thereof, it will be understood by those skilled in art thatvarious changes in form and details may be made therein withoutdeparting from the spirit and scope of the invention.

For example, the desired effects described herein can be accomplished byany combination of resistive and active actuators. For example, althoughcertain effects are described as being accomplished with an activeactuator, the same effect may be accomplished by a resistive actuator ora combination of a resistive actuator and an active actuator (i.e., asin a hybrid interface device).

Although the haptic effect is primarily described as being a simulateddetent in some embodiments of the invention, in alternative embodimentsthe output from the interface device can include desired hapticfeedback. For example, the haptic feedback can be a vibration, a jolt, ahill, a spring force, a texture, etc.

Although the various force profiles and associated control schemes areprimarily disclosed as being based on the position of the object of thedevice, the various force profiles may also be velocity, acceleration,torque, force, and/or time based.

1. A method, comprising: outputting a first haptic feedback as long asan object is moved by a user in a first direction from a first positionalong a path to a second position, the first haptic feedback beingdiscontinued subsequent to the movement in the first direction when theobject is moved along the path in a second direction opposite the firstdirection to a third position; and outputting the first haptic feedbackwhen the object subsequently moves from the third position along thepath in the first direction and past the second position, wherein nofirst haptic feedback is output when the object is moved from the thirdposition to the second position.
 2. The method of claim 1, wherein amagnitude of the first haptic feedback is proportional to a distancebetween the first position and the second position.
 3. The method ofclaim 1, wherein the first haptic feedback is a virtual spring force. 4.The method of claim 1, wherein the movement of the object is associatedwith a simulated movement of a graphical object in a graphical display.5. The method of claim 1, further comprising: outputting a second hapticfeedback based on the movement of the object in the second directionwhen the object is disposed between the first position and the secondposition.
 6. The method of claim 1, wherein the first haptic feedbackoutput based on the movement of the object from the first position isdifferent from a second haptic feedback output based on the movement ofthe object past the first position.
 7. A device, comprising: an objectdisplaceable in at least one degree of freedom with respect to a firstreference point; a sensor configured to output a position signalassociated with a displacement of the object; and an actuator configuredto output a resistive force based on the position signal, wherein theresistive force is output as long as the object is displaced along apath in a first direction away from the first reference point to a firstposition, wherein the resistive force is discontinued when the object isdisplaced along the path in a second direction opposite the firstdirection to a second position, wherein the resistive force is furtheroutput subsequent to the object being moved in the second direction andafter the object is displaced along the path in the first direction pastthe first position, whereby, subsequent to the object being moved in thesecond direction, no haptic effect is felt by a user manipulating theobject while the object is displaced along the path in the firstdirection between the second position and the first position.
 8. Thedevice of claim 7, wherein the degree of freedom is a rotary degree offreedom.
 9. The device of claim 7, wherein the actuator is at least oneof a resistive actuator and an active actuator.
 10. The device of claim7, wherein the resistive force is a simulated spring force.
 11. Thedevice of claim 7, the actuator being a resistive actuator, the devicefurther comprising an active actuator configured to output an assistiveforce based on the displacement of the object in the second direction.12. The device of claim 7 wherein the resistive force is a first hapticeffect, the actuator configured to output a second haptic effect basedon movement of the object in a second direction.
 13. A method,comprising: outputting a haptic feedback as long as an object is movedby a user in a first direction along a path from a first position to asecond position, the haptic feedback being discontinued subsequent tothe movement in the first direction when the object is moved along thepath in a second direction opposite the first direction to a thirdposition, whereby no haptic feedback is felt by the user when the objectis moved in the second direction; and outputting the haptic feedbackwhen the object is subsequently moved in the first direction along thepath past the second position wherein no haptic feedback is output whenthe object is moved from the third position to the second position. 14.A device, comprising: an object manipulable by a user in at least onedegree of freedom with respect to a first reference point; a sensorconfigured to output a position signal associated with a displacement ofthe object; and an actuator configured to output a resistive force basedon the position signal, wherein the resistive force being output as longas the position signal indicates that the object is being displacedalong a oath in a first direction away from the first reference point toa first position, wherein the actuator is further configured todiscontinue outputting the resistive force when the position signalindicates that the object is being displaced along the path in a seconddirection opposite the first direction to a second position, wherein theactuator is further configured to output the resistive force upon theposition signal indicating that the object is displaced along the pathin the first direction past the first position, whereby, subsequent tothe object being moved in the second direction, no haptic effect is feltby the user while the object is displaced along the path in the firstdirection from the second position to the first position.
 15. A method,comprising: outputting a first haptic feedback as long as an object ismoved by a user in a first direction from a first position along a pathto a second position; subsequent to the object being moved in the firstdirection from the first position along the path to the second position,discontinuing the first haptic feedback when the object is moved alongthe path in a second direction opposite the first direction to a thirdposition; and subsequent to the object being moved in the seconddirection to the third position, outputting the first haptic feedbackwhen the object moves in the first direction along the path from thethird position past the second position, whereby no first hapticfeedback is output when the object is moved along the path in the firstdirection from the third position to the second position.
 16. A method,comprising: outputting a first haptic feedback as long as an object ismoved by a user in a first direction from a first position along a pathto a second position; subsequent to the object being moved in the firstdirection from the first position along the path to the second position,discontinuing the first haptic feedback when the object is moved alongthe path in a second direction opposite the first direction to a thirdposition and when the object is moved along the path in the firstdirection from the third position to the second position; and subsequentto the object being moved in the second direction along the path to thethird position, outputting the first haptic feedback when the objectmoves past the second position.